Advertisement

Controlled bushfires damage – not protect – wildlife

The controlled burning of vast swathes of bushland in northern Australia every year is damaging biodiversity, not protecting it, according to the results of an eight-year experiment.

Between 30 and 40 million hectares of bush are burned annually in the Northern Territory. About half of this area is torched maliciously or by accident, but the other half is burnt intentionally by fire managers.

These fires are usually set early in the dry season, when the landscape is still relatively damp. The idea is that these low-intensity fires will reduce the extent of fast-burning, high intensity wildfires later in the season. High intensity wildfires were thought to be more devastating to populations of plants and animals.

“But we found that for many species it doesn’t really matter how intense the fire is – but how frequent it is,” says Alan Anderson at CSIRO, Australia’s national research organisation. “This was a surprise.”

Advertisement

Peter McGauran, Australia’s science minister, welcomes the new findings&colon; “There will always be more to learn about the ecological effects of fire in northern Australia, so it is important that management is continually improved by information from research such as this.”

Bandicoots and possums

Anderson’s team surveyed biodiversity on land and in water across 250 square kilometres of bushland in the Kakadu National Park. They found that numbers of a range of small animals, such as forest birds, bandicoots and possums, dropped severely in land that was burnt annually – whether at a high or low intensity.

These animals required three to five years of no burning for their populations to plateau at high densities. “They will persist in the landscape during frequent burning, but only at very low population densities. This means they’re susceptible to local extinctions if things go wrong,” Anderson says.

Anderson thinks that there will always be an important role for some early-season controlled burning in northern Australia, to help minimise the extent of wildfires. But at present only three per cent of land that is subject to controlled burning is kept free from fire for at least five years. Anderson thinks that figure should be at least trebled.

Various groups are in charge of fire management across northern Australia. These groups are now considering the team’s results, Anderson says.